Method and system for processing semiconductor wafers

ABSTRACT

A method for processing semiconductor wafers includes processing a semiconductor wafer in a processing chamber having upper and lower chambers, decoupling the upper chamber from the lower chamber, cleaning the upper chamber, determining, while decoupled, that a leak rate and a particle count for the upper chamber meets predetermined criteria, and coupling the upper chamber to the lower chamber.

TECHNICAL FIELD OF THE INVENTION

[0001] This invention relates generally to the field of semiconductorsand, more specifically, to a method and system for processingsemiconductor wafers.

BACKGROUND OF THE INVENTION

[0002] Many fabrication techniques are used for processing semiconductorwafers. One such fabrication technique is plasma etching. The plasmaetch process is usually performed in a processing chamber. There aremany requirements for processing chambers used for plasma etching andother semiconductor wafer fabrication processes. For example, it isimportant that vacuum leak rates and particle counts be at, or within,certain levels. Furthermore, processing chambers used for semiconductorwafer processing usually need to be cleaned after they are used.Therefore, semiconductor fabricators strive to process semiconductorwafers at low cost and in a fast and efficient manner.

[0003] One way of preparing processing chambers for use is todisassemble them and clean all the parts with a solvent such as alcohol.The processing chamber is then reassembled, coupled to a lower chamberthat houses the processing equipment, and then a vacuum is pulled on theprocessing chamber. Leak rates and particle counts can then be measuredto see if they are within acceptable levels. If they are not withinacceptable levels, then the processing chamber is taken off the lowerchamber and cleaned further. This wastes considerable time and manpower.Another way of cleaning processing chambers is to outgas them in an ovenusing, for example, a nitrogen gas. Once again, the processing chamberis placed on the lower chamber and the testing of the leak rates andparticle counts is performed as described above. What is needed is amethod or system to ensure a preconditioned processing chamber beforethe processing chamber is set up on the lower chamber before being usedfor processing semiconductor wafers.

SUMMARY OF THE INVENTION

[0004] The challenges in the field of semiconductors continue toincrease with demands for more and better techniques having greaterflexibility and adaptability. Therefore, a need has arisen for a newmethod and system for processing semiconductor wafers.

[0005] In accordance with the present invention, a method and system forprocessing semiconductor wafers is provided that addresses disadvantagesand problems associated with previously developed methods and systems.

[0006] A method for processing semiconductor wafers includes processinga semiconductor wafer in a processing chamber having upper and lowerchambers, decoupling the upper chamber from the lower chamber, cleaningthe upper chamber, determining, while decoupled, that a leak rate and aparticle count for the upper chamber meets predetermined criteria, andcoupling the upper chamber to the lower chamber.

[0007] A mobile system for preconditioning a semiconductor processingchamber having an upper chamber and a lower chamber includes a mobilecart, a hot gas recirculating system coupled to the mobile cart andadapted to couple to the upper chamber, a vacuum source coupled to thecart and adapted to couple to the upper chamber, a leak rate testingsource coupled to the cart and adapted to couple to the upper chamber,and a particle count testing source coupled to the cart and adapted tocouple to the upper chamber.

[0008] Embodiments of the invention provide numerous technicaladvantages. For example, a technical advantage of one embodiment of thepresent invention is that there is a reduction in time from when asemiconductor wafer is processed to preconditioning a processing chamberfor the next processing cycle. Another technical advantage of oneembodiment of the present invention is the reduction of processingvariables such as processing chamber vacuum leak rates and processingchamber particle counts. Utilizing one embodiment of the presentinvention results in a processing chamber being ready for use as soon asone processing cycle is finished using another preconditioned processingchamber. The preconditioned processing chamber is held under vacuum andthe leak rates and particle counts are already known; therefore, theprocessing chamber just needs to be set up and used. Other technicaladvantages are readily apparent to one skilled in the art from thefollowing figures, descriptions, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] For a more complete understanding of the invention, and forfurther features and advantages, reference is now made to the followingdescription, taken in conjunction with the accompanying drawings, inwhich:

[0010]FIG. 1 is an elevation view of one embodiment of a processingchamber having upper and lower chambers for processing semiconductorwafers in accordance with the present invention;

[0011]FIG. 2 is a flowchart demonstrating one method of processingsemiconductor wafers in accordance with the present invention; and

[0012]FIG. 3 is an elevation view of one embodiment of a mobile cart forpreconditioning an upper chamber of a processing chamber in accordancewith the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0013] Embodiments of the present invention and their advantages arebest understood by referring now to FIGS. 1 through 3 of the drawings,in which like numerals refer to like parts.

[0014]FIG. 1 is an elevation view of a processing chamber 100 having anupper chamber 102 and a lower chamber 104 for processing semiconductorwafers 106. One example of processing chamber 100 is the Silicon EtchDPS Plus Centura™ from Applied Materials™. However, other types ofprocessing chambers can be used for many different types ofsemiconductor wafer processes. One example of such a semiconductor waferprocess is plasma etching.

[0015] In one embodiment, semiconductor wafers 106 are housed in upperchamber 102, which is where the plasma etch process, or othersemiconductor wafer process, is accomplished. Lower chamber 104 is theportion of processing chamber 100 where processing variables, such aspressure, temperature, and RF frequency are produced and/or delivered toupper chamber 102. Since semiconductor wafer processing requires a cleanatmosphere, upper chamber 102 needs to be preconditioned before use.Therefore, upper chamber needs to be cleaned periodically, such as aftera plasma etch process. Since this normally requires disassembly, removaland/or replacement of parts, cleaning, and reassembly, then significanttime is wasted in processing semiconductor wafers. Not only is timewasted, but extra manpower may be required to precondition theseprocessing chambers, thereby wasting additional money and hurtingefficiency. Thus, a method of processing semiconductor wafers that isfast and efficient and done at low cost is desired. One such method isshown in FIG. 2.

[0016]FIG. 2 is a flowchart illustrating one method for processingsemiconductor wafers in accordance with the present invention. Asemiconductor wafer 106 is processed in processing chamber 100 havingupper chamber 102 and lower chamber 104 at step 200. As described above,this process could be a plasma etch process to, for example, etchpolysilicon or metal. After processing semiconductor wafer 106, upperchamber 102 needs to be cleaned. Therefore, upper chamber 102 isdecoupled from lower chamber 104 at step 202, and upper chamber 102 iscleaned at step 204.

[0017] There are many ways to clean upper chamber 102. For example,upper chamber 102 can be cleaned with a hot gas recirculating system(“HGRS”) 301 as shown in FIG. 3, which is well known in the art ofsemiconductor wafer processing. In one embodiment, HGRS 301 is coupledto a cart 300, which is described in detail below, for the efficient andcost-effective processing of semiconductor wafers. Upper chamber 102 mayalso be cleaned by outgassing in an oven or by disassembling andcleaning the various parts of upper chamber 102 with a solvent such asalcohol.

[0018] After cleaning upper chamber 102 at step 204, upper chamber 102is reassembled, if necessary, and preconditioned. This preconditioninginvolves determining, while upper chamber 102 is decoupled from lowerchamber 104, that certain atmospheric conditions such as a leak rate anda particle count meet certain predetermined criteria, as indicated bybox 206. Leak rates and particle counts are important parameters whenprocessing semiconductor wafers 106. Leak rates and particle counts needto be at, or within, certain levels before semiconductor wafers 106 areprocessed. In one embodiment, the leak rate is a maximum of onemillitorr, and the particle count is a maximum of ten particles perminute. After the leak rate and the particle count reach predeterminedlevels, then upper chamber 102 is coupled to lower chamber 104 at step208. Processing chamber 100 is then ready to process semiconductorwafers without having to check the leak rate and the particle count.

[0019] Preconditioning upper chamber 102 while decoupled from lowerchamber 104 saves considerable time and manpower, as compared toconventional techniques, when processing semiconductor wafers. Forexample, if the leak rate and particle count are not known when upperchamber 102 is coupled to lower chamber 104, then the leak rate andparticle count have to be checked after processing chamber 100 is putunder a vacuum. If the leak rate and/or particle count is not at itspredetermined value, then upper chamber 102 is reconditioned againbefore being coupled to lower chamber 104. The vacuum and testingprocedures are performed again to make sure processing chamber 100 isready for processing semiconductor wafers. The reconditioning ofprocessing chamber 100 may entail cleaning upper chamber 102 again, suchas with HGRS 301, thereby consuming additional time. As described above,HGRS 301 may be coupled to cart 300. One example of such a cart is shownin FIG. 3.

[0020]FIG. 3 is an elevation view of a cart 300 for preconditioningupper chamber 102 in accordance with one embodiment of the presentinvention. Cart 300 includes a base 302 and a support plate 304 coupledto base 302 that is operable to support upper chamber 102 of processingchamber 100. Cart 300 also includes HGRS 301 coupled to base 302 andadapted to couple to upper chamber 102, a vacuum source 319 adapted tocouple to upper chamber 102, a leak rate testing source adapted tocouple to upper chamber 102, and a particle count testing source 321adapted to couple to upper chamber 102. Cart 300 may also include avibration isolation system 312 disposed between base 302 and supportplate 304.

[0021] Base 302 may be formed from any type of material and in anyconfiguration suitable for supporting support plate 304, upper chamber102, and additional desired equipment. Base 302 may have wheels 316, asshown in FIG. 2, to allow cart 300 to be mobile, and base 302 may havehandles 314 for easy handling and transportation of cart 300. Base 302may also have a cover 320 for protection of upper chamber 102.

[0022] Support plate 304 supports upper chamber 102 and may be formedfrom any type of material and in any configuration suitable forsupporting upper chamber 102. In one embodiment, support plate 304 ismade of aluminum. Support plate 304 may also include a heating system318, which is used to heat upper chamber 102 to a desired temperature.This temperature may be desired for such things as alignment purposeswhen coupling upper chamber 102 to lower chamber 104, or for processingpurposes so that upper chamber 102 is ready for processing semiconductorwafers 106 at, or near, its operating temperature, thus reducingprocessing time.

[0023] HGRS 301, as described above, is well known in the art ofsemiconductor wafer processing. In the embodiment shown in FIG. 3, HGRS301 is coupled to base 302 and adapted to couple to upper chamber 102.HGRS 301 cleans upper chamber 102 to prepare upper chamber 102 for itsnext processing cycle. In one embodiment, HGRS 301 includes inlet valve306, inlet bellows 307, riser 308, outlet bellows 309, and outlet valve310, which work together to cycle purge gas through upper chamber 102 asshown by arrow 350. In one embodiment, the gas is a nitrogen gas that isheated to a temperature of approximately 130° C.; however, other typesof gas may be used as well as other temperatures. HGRS 301 may alsoinclude other equipment to cycle purge gas through upper chamber 102.

[0024] Vacuum source 319 may be any type of vacuum source that isadapted to couple to upper chamber 102. Vacuum source 319 may or may notbe coupled to cart 300. Vacuum source 319 may hold upper chamber 102under a vacuum, or other desired pressure, for any period of timedesired. Once upper chamber 102 is placed under a vacuum, or otherdesired pressure, upper chamber 102 may then be checked for its leakrate and particle count using leak rate testing source 320 and particlecount testing source 321.

[0025] Leak rate testing source 320 may be any type of leak rate testingsource adapted to couple to upper chamber 102. Leak rate testing source320 may or may not be coupled to cart 300. Leak rate testing source 320is used to test upper chamber 102 for a desired value of vacuum leakrate. In one embodiment, the leak rate is a maximum of one millitorr.

[0026] Particle count testing source 321 may be any type of particlecount testing source adapted to couple to upper chamber 102. In oneembodiment, particle count testing source 321 is an in situ particlemonitor from HYT, which is well known in the art of semiconductorprocessing. Particle count testing source 321 may or may not be coupledto cart 300 and is used to test upper chamber 102 for a desired particlecount. In one embodiment, the particle count is a maximum of tenparticles per minute.

[0027] Vibration isolation system 312 may be any type of vibrationisolation system suitable for isolating support plate 304 fromvibrations emanating from base 302 or the environment. In oneembodiment, vibration isolation system 312 comprsies rubber members.

[0028] Once the leak rate and the particle count of upper chamber 102reach desired values, upper chamber 102 may then be held under a vacuumuntil ready for the next processing cycle. This preconditioning allowsconsiderable savings in semiconductor wafer processing time by having aprepared processing chamber, with a known leak rate and a known particlecount, ready for substantially immediate use.

[0029] In operation, one embodiment of the present invention includesprocessing chamber 100 processing semiconductor wafers 106. After theprocess is performed, semiconductor wafers 106 are then removed. Upperchamber 102 is then decoupled from lower chamber 104 so upper chamber102 may be cleaned. Upper chamber 102 may be placed on support plate 304of cart 300, and HGRS 301 may circulate hot nitrogen gas to upperchamber 102 to precondition upper chamber 102 for the next processingcycle. After HGRS 301 cycle purges hot nitrogen gas through upperchamber 102, HGRS 301 is shut down and a vacuum is pulled on upperchamber 102. Then the leak rate and particle count of upper chamber 102are checked with leak rate testing source 320 and particle count testingsource 321 until predetermined values are reached. These predeterminedvalues depend on the process for which upper chamber 102 is to be used.Once these predetermined values are reached, upper chamber 102 is heldunder the vacuum until ready for use. Cart 300, if it has wheels such aswheels 316, may be moved from location to location depending on wherethe next processing system takes place. For example, cart 300 mayreceive upper chamber 102 after upper chamber 102 is finished processingsemiconductor wafers 106, then moved to a preconditioning station, andthen moved to the next processing station. Preconditioning upper chamber102 using mobile cart 300 allows for less downtime associated with theprocessing of semiconductor wafers.

[0030] Although embodiments of the invention and their advantages aredescribed in detail, a person skilled in the art could make variousalternations, additions, and omissions without departing from the spiritand scope of the present invention as defined by the appended claims.

What is claimed is:
 1. A method for processing semiconductor wafers,comprising: processing a semiconductor wafer in a processing chamberhaving upper and lower chambers, wherein the upper chamber houses thesemiconductor wafer and the lower chamber comprises processing equipmentoperable to process the semiconductor wafer; decoupling the upperchamber from the lower chamber; cleaning the upper chamber; determining,while decoupled, that a leak rate and a particle count for the upperchamber meets predetermined criteria; and coupling the upper chamber tothe lower chamber.
 2. The method of claim 1, further comprising placingthe upper chamber under a vacuum.
 3. The method of claim 1, wherein theleak rate is a maximum of one millitorr per minute.
 4. The method ofclaim 1, wherein the particle count is a maximum of ten particles perminute.
 5. The method of claim 1, wherein cleaning the upper chambercomprises cycle purging hot gas through the upper chamber with a hot gasrecirculating system.
 6. The method of claim 5, and further comprisingcoupling the hot gas recirculating system to a mobile cart, and whereinthe hot gas is nitrogen.
 7. The method of claim 6, and furthercomprising: coupling a vacuum source to the mobile cart and operativelycoupling the vacuum source to the upper chamber; coupling a leak ratetesting source to the mobile cart and operatively coupling the leak ratetesting source to the upper chamber; and coupling a particle counttesting source to the mobile cart and operatively coupling the particlecount testing source to the upper chamber.
 8. The method of claim 1,further comprising holding the upper chamber under a vacuum until theupper chamber is coupled to the lower chamber.
 9. The method of claim 1,wherein processing at least one semiconductor wafer in a processingchamber comprises plasma etching.
 10. A method for preconditioning asemiconductor processing chamber, comprising: decoupling an upperchamber from a lower chamber, the upper chamber and lower chamberforming the semiconductor processing chamber when coupled together;placing the upper chamber under a vacuum; cycle purging hot nitrogen gasthrough the upper chamber with a hot gas recirculating system;determining that a leak rate and a particle count for the upper chambermeet predetermined criteria; and coupling the upper chamber to the lowerchamber.
 11. The method of claim 10, wherein the leak rate is a maximumof one millitorr per minute.
 12. The method of claim 10, wherein theparticle count is a maximum of ten particles per minute.
 13. The methodof claim 10, wherein cycle purging hot nitrogen gas through the upperchamber with a hot gas recirculating system comprises coupling the hotgas recirculating system to a mobile cart.
 14. The method of claim 13,and further comprising: coupling a vacuum source to the mobile cart andoperatively coupling the vacuum source to the upper chamber; coupling aleak rate testing source to the mobile cart and operatively coupling theleak rate testing source to the upper chamber; and coupling a particlecount testing source to the mobile cart and operatively coupling theparticle count testing source to the upper chamber.
 15. The method ofclaim 10, further comprising holding the upper chamber under a vacuumuntil the upper chamber is coupled to the lower chamber.
 16. A mobilesystem for preconditioning a semiconductor processing chamber having anupper chamber and a lower chamber, comprising: a mobile cart; a hot gasrecirculating system coupled to the mobile cart and adapted to couple tothe upper chamber; a vacuum source coupled to the cart and adapted tocouple to the upper chamber; a leak rate testing source coupled to thecart and adapted to couple to the upper chamber; and a particle counttesting source coupled to the cart and adapted to couple to the upperchamber.
 17. The system of claim 16, wherein the mobile cart comprises:abase; and a support plate coupled to the base for supporting the upperchamber of the processing chamber.
 18. The system of claim 17, andfurther comprising: a vibration isolation system disposed between thebase and the support plate; at least one wheel coupled to the base; atleast one handle coupled to the base; and a chamber cover coupled to thebase.
 19. The system of claim 17, and further comprising a heatingsystem coupled to the support plate for heating the upper chamber. 20.The system of claim 16, wherein the hot gas recirculating system isoperable to cycle purge hot nitrogen gas through the upper chamber. 21.The system of claim 20, and wherein the hot gas recirculating systemcomprises: an inlet valve operable to receive hot nitrogen gas; an inletbellows coupled to the inlet valve and operable to transport the hotnitrogen gas to the upper chamber; an outlet bellows operatively coupledto the upper chamber and operable to transport the hot nitrogen gas awayfrom the upper chamber; and an outlet valve coupled to the outletbellows and operable to relinquish the hot nitrogen gas.